Improvement in saw-frames



w. CUTTER.

Improvement in Saw-Frames.

Patented oct. 15,1872.

raf/Leffe g MM Nu/(5%.

UNITED STATES PATENT OFFICE,

Y WILLIAM COTTER, OF LONDON, ENGLAND, ASSIGNOR OF ONE-HALF HIS RIGHT TO EDWARD NEWTON, OF SAME PLACE.

IMPROVEMENT IN SAW-FRAMES.

Specication forming part of Letters Patent No. 132,140, dated October 15,1872.

To all whom it may concern:

Be it known that I, WUJLIAM COTTER, of London, England, have invented certain Improvements in Bow Saw-Frames, to be called Cotters eXible bow saw-frame, of which the following is a speciiication:

This invention relates to certain improvements in the construction of bow saw-frames,

whereby the saw-blade is more easily adjusted to or removed from the frame, and the operation of cutting is also greatly facilitated, more especially for sharp curves and fret Work. More than double the depth of cut may also be obtained than with the ordinary bow-saw, in which the stretcher of the frame is straight and rigid. rIhe saw-blade itself has, in the old arrangement, to maintain the requisite adjustment of the parts of the frame, thereby presentingat all times a difculty in inserting" the saw-blades. By my invention I dispense altogether with the rigid bar-stretcher, and in place thereof employ a stretcher (by preference semicircular) rising from the fulcrums, through or over which is attached a tensionbar or bars, adjustable by thumb-screws on either side of the frame for regulating the tension of the saw-blade. I also employ an improved spindle-adjustment for locking the saw-blade in position, by which it is prevented from falling out, such falling out being a sourceV of annoyance and loss of time in manipulating with the old bow-saw. The handles are also constructed so as to regulate the tension of the saw, and I `employ set-screws for fixing the spindles so that the saw-blade is prevented from turning while-in use. The large amount of play of the side bars of the frame obtained by my improvements, in conjunction with the screw ferrule arrangement, also allow sawblades of different lengths being used, which l could not be done with the old bow-saw frame,

and the iiexibility of the frame prevents the breakage of the saw-blade from a sudden jar,

a saw-blade applied thereto; and Figs. 2, 3, and 4, details on a larger scale of the spindlelockin g arrangement.

In Fig. 1, a a are the side bars or armatures of the frame, and b is the improved stretcher, made by preference of bent wood so as to form a spring, but which may be made of steel or other suitable metal. rIhe ends of this stretcher are knuckle-jointed at c c to the side-bars a, a, and the upper ends of these bars are connected to the spring-stretcher b by the tensionrods di d, furnished at their outer ends with thumb-screws e e, their inner ends being screwthreaded and passing, as shown by the dotted lines, into holes in the stretcher b and through female screws cut in the metal pieces ff, which pass through the whole thickness of this stretcher. By this arrangement if the thumbscrews be turned the side-bars a a will be moved on the joints c c and the lower ends of the bars will thereby be moved toward or from one another (according to the direction in which the tension-rods are turned) and thus regulate the tension of the saw-blade. The handles g g are each furnished with a spindle, h, and sliding tube h passing through holes in the lower ends of the side bars a a of the frame, as shown by the sectional part of Fig. l; the inner ends of these spindles re- 'ceive the ends ofthe saw-blade, as hereinafter described. On each handle, outside the frame,

I ix a ferrule, z', cut with a male screw, and on this ferrule I pass another ferrule, j, having a female screw cut therein, a washer, 7c, being placed between the ends of the ferrules j'and the side-bars a a. rIhis screw-ferrule arrangement allows oi' regulating the tension of the saw-blade, for by merely turning the outer ferrules j by the hands the spindles h h, holding the ends of the saw-blade, will be moved outward or inward, according to the direction in which the Vferrules j j are turned. Hare set-screws fixing the spindles h, and thereby preventing the saw-blade turning when being used. These set`- screws pass through female screws cut in the metal rods m m, which fit in holes passing through the side bars a, a.

I will now describe the spindle-locking arrangement for holding the ends of the sawblade: Figf2 shows a plan of part of the spindle and its tube, and of the saw-blade q detaehed, the spindle and tube being shown in the position to receive the end of the saw,- blade 5 Fig. 3, side elevation of same, and also end elevation of spindle; Fig. 4, side elevation, showing the end ofthe saw-blade applied to the spindle and looked by the tube. The spindle h has a longitudinal slot, n, cut completely through it, the width of the slot being somewhat greater than the thickness of the saw-blade; the spindle has, also, a transverse slot, o, cut in it, and which is to receive the pin p of the saw-blade. On thespindle h is placed, soy as to slide freely thereon, a tube, h', also cut with a longitudinal and a transverse slot, as seen in plan, Fig. 2. By this arrangement to ix the end of the saw-blade 'in the spindle the end of the saw-blade must be passed into the longitudinal slot u' of the spindle, and the pin p in the transverse slot o; the tube h must then be turned a quarter of a revolution so as to bring its longitudinal slot in a line with the pin p, and then moved forward until the pin is brought into the transverse slot of the tube h', which latter is finally turned another quarter of a revolutiol'I/s) as to occupy the position shown in 4, and the end of the saw-blade will be firmly locked. To remove the end of the saw-blade the tube h must be moved in the opposite directions to that described for lookin g it. The pin p may be loose in the saw-blade, and can be headed at both ends, as it does not require to be removed.

Having thus described my invention and the manner of operating the same, I wish it to be understood that the arrangements described and shown may be modified without departing from the principle of the inventionfor example, instead of employing two tension-rods, d d, one only may be employed, iixed at one end to one of the side bars a, and passing above the stretcher b, and be furnished with a thumb-nut at the other end. The screwferrules i j may also be dispensed with, and ordinary hinges may be employed instead of the knuckle-joints o c; but

What I claim is- The spindle -looking apparatus h h', setscrews l l, and screw-ferrules t' j, when combined and operating together, as described.

In testimony whereof I, the said WILLIAM GOTTER, have hereunto set my hand and affixed my seal this twenty-ninth day of J une, one thousand eight hundred and seventy-two.

WM. OOTTER. [L. s] Witnesses: y

EDWARD NEWTON, G. F. REDFERN. 

